A phosphorite is a sedimentary rock composed chiefly of phosphate minerals. The Proterozoic era (also called the Algonkian) is the geologic time between the Archean and the Paleozoic, with the Archean beginning about 3.9 billion years ago and involving the first appearance of sedimentary rocks and the first primitive organisms at the bottom of the oceans. In paleontology, the term "radiation" refers to a diverging and diversifying spread of animals or plants into new environments with a resultant production of new evolutionary forms, and the Ediacaran radiation refers to an assemblage (until now the oldest) of soft- bodied marine animals, the assemblage first discovered in the Ediacara Hills in Australia. The algae comprise a large mixed group of photosynthetic and essentially single-celled plants, and are considered ancestral to modern green plants. Thalli are primitive types of plant bodies not differentiated into stems, leaves, and roots; the term also refers to the gametophyte generation (the phase of the plant life cycle producing reproductive cells) of some ferns and lichens. The term "cleavage stages" refers to the early stages of embryo formation when the egg cell rapidly divides into smaller and smaller cells. The "Bilateria" are a major division of the animal kingdom comprising all forms with bilateral symmetry, and the term "bilaterians" refers to the first such forms appearing after the emergence of protozoa. The term "phylogeny" refers to the evolutionary history of an organism or group of organisms. ... ... Xiao et al (3 authors at 2 installations, US CN) report the discovery of phosphorites of the late Neoproterozoic (570 +- 20 million years ago) in the Doushantuo Formation, southern China, an apparent exceptional record of multicellular life from just before the Ediacaran radiation of macroscopic animals. Abundant thalli with cellular structures preserved in 3-dimensional detail show that late- Proterozoic algae already possessed many of the anatomical and reproductive features seen in modern marine flora. Embryos preserved in early cleavage stages indicate the divergence of lineages leading to bilaterians may have occurred well before their macroscopic traces or body fossils appear in the geological record. The authors suggest that discovery of these fossils shows that the early evolution of multicellular organisms is amenable to direct paleontological inquiry, and that paleontological observations, together with insights from molecular phylogeny and developmental genetics, can facilitate a modern integration of phylogeny, development, and paleontology that extends deeply into evolutionary history to address the early evolution of multicellular life.

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